In-plane RFID antenna

ABSTRACT

Disclosed is an apparatus and methodology for providing an RFID device for integration into a tire. A printed circuit board (PCB) is provided with notches in opposed ends of the PCB that are provided with guide portions as a part of the notches that function as threads to guide an end portion of a matching single pitch helical antenna into appropriately placed vias on the PCB. Threading of the helical antenna is assisted by use of an assembly jig having antenna guiding channels and PCB retaining positioning elements.

FIELD OF THE INVENTION

The present subject matter is directed to RFID (Radio FrequencyIdentification) devices for integration into tires. More particularly,the present subject matter relates to RFID apparatus and methodologiesfor providing improved antenna connection configurations for suchdevices.

BACKGROUND OF THE INVENTION

Electrical circuits are used in a variety of environments that canpresent particular physical, chemical, and electrical factors for whichthe circuit must either be protected or be designed to endure. Thepresent invention primarily concerns physical factors such as mechanicalstress leading to fatigue, which in turn can cause a circuit malfunctionby physically breaking or weakening a specific part of the circuit. Atypical location for such malfunction is at or near the point ofconnection of a wire, lead, or other conductor to an electrical circuit.In circumstances where the wire and the connected-to circuit may move orrotate relative to one another, the wire may incur a concentration ofmechanical stress and/or fatigue at or near the point of connection tothe circuit. Mechanical stresses such as repeated bending or twisting,for example, can lead to a weakening of the wire until a break occurs.

Electronics integrated within a tire or other product offer potentialadvantages such as asset tracking and measurement of physical parametersas, for example, temperature and pressure. For purposes of the presentdisclosure, the phrase ‘integrated within a tire’ denotes anyassociation of an electronics device with a tire including, but notlimited to, encased or adhered entirely or partially within or to anyportion of the tire, or attached to an inner or outer surface of thetire.

Often many of these systems rely on a wireless data link to communicatewith an information system outside of the vehicle. Such informationsystems may include, as non-limiting examples, on-board computersystems, drive-by interrogators, or hand-held interrogators. Inaddition, the types of data communicated over such wireless data linksare wide and varied and include such as not only the previouslymentioned temperature and pressure but also other physical parameterssuch as tire rotation speed as well as data corresponding tomanufacturing data and a host of other information. What ever the typeof data transmitted, the wireless data link requires an antenna to beattached to the electronics in the tire. If the electronics and/orantenna are adhered to the tire rubber, flexing of the tire, either dueto the tire building process or normal use can cause the antenna toseparate from the electronics due to cracking, breaking, or fatigue.

U.S. Pat. No. 7,196,616 (Sinnett et al.) discloses apparatus andmethodology for providing a graduated stiffness, strain-resistantelectrical connection. A material is configured around the lead and nearthe point of connection to the circuit so as to create a region ofdecreasing flexibility or graduated stiffness near the point ofconnection. Another example of a tire electronics system can be found inU.S. Pat. No. 7,102,499 (Myatt), which concerns an electroniccommunications device for a tire that includes a radio device and anantenna to be attached to or embedded in a tire.

U.S. Patent Application Publication No. US 2007/0274030 A1 (Robert) alsorelates to tire electronics, and more particularly discloses anelectronic module designed to be incorporated in a tire comprising afunctional device, a support and at least one device for electricallyconnecting a wire and a device for mechanically fixing the wire,separate from the electrical connection device, for mechanically fixingthe wire to the support.

The PCT Application published as International Publication Number WO2006/098710 A1 (Sinnett et al.) is directed to a strain-resistantelectrical connection for coupling an antenna or other conductive leadto a circuit. This published application describes a technique similarto that described with reference to the known devices illustrated hereinin FIGS. 2A and 2B and described later in comparison to the presentsubject matter.

Other similar subject matter is described in JP2007049351A entitled“Electronic Tag For Tire And Pneumatic Tire” as an electronic tag with acoil-shaped antenna connected to an integrated circuit chip. Thecoil-shaped antenna includes dual pitch wound portions with the higherpitch winding coupled to the integrated circuit chip. U.S. Pat. No.6,836,253 B2 (Strache et al.) describes a transmitter or receiver unitfor building into elastic structures including tires. The unit mayinclude an antenna taking several forms including a coiled-wireconfiguration.

While various implementations of tire electronics devices such as RFIDdevices in tire electronic systems have been developed, and whilevarious methodologies have been developed to relieve stress atelectrical coupling points, no design has emerged that generallyencompasses all of the desired characteristics as hereafter presented inaccordance with the present technology.

SUMMARY OF THE INVENTION

In view of the recognized features encountered in the prior art andaddressed by the present subject matter, improved apparatus andmethodology for providing an improved antenna configuration andelectrical connection thereof for RFID devices has been provided.

In an exemplary configuration, an RFID device for integration into atire, has been provided comprising a printed circuit board (PCB) havingtop and bottom surfaces delineated by opposed end portions and opposedside portions, a plurality of conductive traces on the top surface ofsaid PCB, a notch formed in one end of the PCB, a plated through viapiercing the PCB from the top surface to the bottom surface, aconductive trace element surround the via at the top surface of the PCB,the trace element electrically coupled to the plurality of conductivetraces, a conductive solder pad surrounding said via at the bottomsurface of said PCB and extending for a predetermined distance in thedirection of the side portions of the PCB, and an antenna element havingan end portion positioned within the notch and within a plane defined bythe top surface of the PCB, wherein a portion of the end portion passesthrough the via from the top surface to the bottom surface and iselectrically connected to the conductive trace element surround the viaat the bottom surface of the PCB.

In accordance with aspects of certain embodiments of the present subjectmatter, methodologies are provided for assembling an RFID devicecomprising providing a printed circuit board (PCB) having top and bottomsurfaces, opposed end portions, and opposed side portion, providing asingle pitch helical antenna element, forming notches in the opposed endportions such that portions of the notches are configured as guideportions having pitches corresponding to the single pitch of the helicalantenna element, providing plated through vias in the PCB positioned tocorrespond to the pitch of the single pitch helical antenna element,providing an assembly jig comprising support and retaining structuresfor the PCB, providing antenna supporting channels in a surface of theassembly jig, retaining the PCB on the assembly jig with the bottomsurface exposed, placing an antenna element in a support channel,threading an end portion of the antenna element through a via in the PCBby rotating and advancing the antenna element within the supportchannel, and soldering the end portion of the antenna to a portion ofthe plated through via on the bottom surface of the PCB to produce anassembled device.

Additional objects and advantages of the present subject matter are setforth in, or will be apparent to, those of ordinary skill in the artfrom the detailed description herein. Also, it should be furtherappreciated that modifications and variations to the specificallyillustrated, referred and discussed features and elements hereof may bepracticed in various embodiments and uses of the invention withoutdeparting from the spirit and scope of the subject matter. Variationsmay include, but are not limited to, substitution of equivalent means,features, or steps for those illustrated, referenced, or discussed, andthe functional, operational, or positional reversal of various parts,features, steps, or the like.

Still further, it is to be understood that different embodiments, aswell as different presently preferred embodiments, of the presentsubject matter may include various combinations or configurations ofpresently disclosed features, steps, or elements, or their equivalents(including combinations of features, parts, or steps or configurationsthereof not expressly shown in the figures or stated in the detaileddescription of such figures). Additional embodiments of the presentsubject matter, not necessarily expressed in the summarized section, mayinclude and incorporate various combinations of aspects of features,components, or steps referenced in the summarized objects above, and/orother features, components, or steps as otherwise discussed in thisapplication. Those of ordinary skill in the art will better appreciatethe features and aspects of such embodiments, and others, upon review ofthe remainder of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1A illustrates a top view of an exemplary RFID device in accordancewith present technology for incorporation into a tire;

FIG. 1B illustrates an end view of the RFID device in enlarged scaletaken from the viewpoint of arrows 1B-1B of FIG. 1A;

FIG. 1C illustrates a bottom view of the device of FIG. 1A;

FIG. 1D illustrates a printed circuit board (PCB) in accordance with thepresent technology in enlarged view to illustrate unique aspects of thePCB;

FIG. 2A illustrates a known RFID device for comparison with the presenttechnology;

FIG. 2B illustrates an end view of the RFID device of FIG. 2A inenlarged scale taken from the viewpoint of arrows 2B-2B of FIG. 2A; and

FIG. 3 illustrates an exemplary assembly methodology for the device ofthe present subject matter illustrating the use of an alignment jigassembly.

Repeat use of reference characters throughout the present specificationand appended drawings is intended to represent same or analogousfeatures or elements of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As discussed in the Summary of the Invention section, the presentsubject matter is particularly concerned with apparatus andmethodologies for providing an improved antenna configuration andelectrical connection thereof for RFID devices.

Selected combinations of aspects of the disclosed technology correspondto a plurality of different embodiments of the present invention. Itshould be noted that each of the exemplary embodiments presented anddiscussed herein should not insinuate limitations of the present subjectmatter. Features or steps illustrated or described as part of oneembodiment may be used in combination with aspects of another embodimentto yield yet further embodiments. Additionally, certain features may beinterchanged with similar devices or features not expressly mentionedwhich perform the same or similar function.

Reference will now be made in detail to the presently preferredembodiments of the subject RFID device. Referring now to the drawings,FIG. 1 illustrates a top view of an exemplary RFID device 100constructed in accordance with present technology for incorporation intoa tire. Those of ordinary skill in the art will appreciate that whilethe device described herein has particular use in relation to tiretechnology, such is not a limitation of the device itself as such devicemay be employed with other technologies as well where damage may occurto the device or to the electrical connections as a function of inducedstress. A shipping pallet or container for moving goods that may beidentified by way of the RFID device 100 is one such example.

As may be seen from FIG. 1A, RFID device 100 includes a printed circuitboard (PCB) 102 on which is provided a number of conductive traces 104.An integrated circuit (IC) device 120 is mounted to PCB 102 inconventional manner and is electrically connected to traces 104 and, viaportions 130A, 130B of traces 104 to antenna elements 110, 112. Itshould be appreciated that the illustrated antenna elements 110, 112 arenot drawn to scale and are intended to be extended following theillustrated helical form to a length corresponding to at leastapproximately the resonant frequency of the RFID system.

Trace 104 portions 130A, 130B surround plated through vias 134A, 134B(FIGS. 1C and 1D) that pass through PCB 102 and connect to a pair ofsolder pads 130C, 130D on the bottom surface of PCB 102 (FIG. 1C). Asbest illustrated in FIG. 1C, end portion 114 of helical antenna element112 continues in an unbroken pattern through the via-holes 134A, 134Band around until it touches (at 116 on solder pad 130C) solder pads130C, 130D that extend substantially between the side portions of PCB102 on the bottom of PCB 102. When end portion 114 of helical antennaelement 112 touches solder pad 130C, it may be bonded to the solder padsuch as by soldering as representatively illustrated at 118. Of course,in final assembly both antennas are bonded, for example by soldering toboth solder pads. The connection to solder pad 130C has been shown priorto soldering to better illustrate the touching of the end of the antennato the solder pad prior to soldering.

Bonding antenna portions 110, 112 to PCB 102 in this manner achievessignificant improvement over similar devices in that such bonding of theantenna coiled wire helps to prevent delamination of the traceconductors on the surface of PCB 102. In addition, soldering antennaelements 110, 112 on the side of PCB 102 opposite IC chip 120significantly reduces the chances of excess solder and of solder wickingdown the similar previously known antenna helix 210, 214, 212, 216 asillustrated in FIG. 2A.

Addition benefits derive from attaching the antenna elements in thismanner. For example, significant savings are achieved in cost andconvenience over the attachment techniques previously used such asillustrated in FIG. 2A. As illustrated in FIG. 2A, dual pitch,individually wound antenna elements as illustrated at 210, can now bereplaced with longer single pitch coils that may be cut to length atassembly time.

The previously known design illustrated in FIGS. 2A and 2B employed adual pitch antenna helix configuration where higher pitch portions 214,216 were provided to assist in soldering the antenna elements toconductive traces 204. Such placement of the previously known antennaelements where the outer surface of the antenna helix was in contactwith and soldered to the upper surface of PCB 202 produced a devicehaving a thickness of the outer diameter (OD) of the spring used as anantenna plus the thickness T′ of the PCB 202.

Such thickness produced, in exemplary known configurations, a rigid zonebetween the antenna attachment points of 7 mm. In a tire environment,this causes the buildup of excess strain along the length of the rigidzone that must be accommodated off the ends of the PCB. Suchaccommodation of excess strain is believed to be one cause for fatiguefailures of the antenna. By contrast, and in accordance with presenttechnology, by relocating the antenna attachment point to the oppositesided of the PCB 102 the rigid distance between antenna attachmentpoints may be reduced to only about 3 mm, resulting in an improvement of57%.

In addition, such placement of the attachment point of the previouslyused dual pitch helical antenna elements produced a device with anindeterminate location for the free end of the helical element inrotation. This placement allowed for the possibility that such end mightbe away from the PCB and create a harmful sharp point. In accordancewith present technology, an end portion of the helical antenna elementis located in a plated through hole or via so that the end of theantenna is in a well-controlled position, adjacent to the PCB and unableto create a sharp point.

Further still, by designing PCB 102 such that antenna elements 110, 112may be placed within the plane of PCB 102 multiple advantages can berealized. First, a device can be provided with a total thickness equalto or only slightly larger than the OD of the antenna coil. Second, byredesigning the PCB 102 with shaped features that define the location ofthe helical spring antenna wire, alignment with the holes 134A, 134B foreasy assembly is achieved. Third, by placing the antenna elements withinthe plane of PCB 102 and, more specifically, between arm portions108A-108D, a graduated stiffness of the electrical connection isachieved through the synergistic cooperation of the arms, antennaelement and a non-conductive elastomeric material 150 (FIG. 1A) betweenthe arms and enveloping the antenna element as well as embedding allparts of the assembled device. In an exemplary embodiment, all portionsof the assembled device may be coated with a bonding agent such asChemlok® available from LORD Corporation, prior to embedding theassembled device in the non-conductive elastomeric material. Fourth,placing the antenna within the plane of the PCB 102 allows anopportunity to increase the thickness T (FIG. 1B) of PCB 102 to therebyprovide a stronger assembled device than that of previously knowndevices such as illustrated in FIG. 2B having a PCB 202 with lessthickness T′.

With further attention to FIG. 1D, it will be seen that PCB 102, inaccordance with present technology, is provided with notched portions120A, 120B between arms 108A, 108B and 108C, 108D, respectively, thatare somewhat similar to the arm portions illustrated in FIG. 2A. Thenotch portions 120A, 120B according to present technology, however, areconfigured to provide curved shaped portions 124A, 124B between linearregions 122A, 122B on one end of PCB 102 and similar curved shapedportions 128A, 128B between linear regions 126A, 126B on the other endof PCB 102 that define the location of the helical spring wire antennaelements 110, 112. In particular, shaped notch portions 120A, 120B aredesigned to correspond to the pitch of the helical antenna elements 110,112 so that the antenna helix may be easily threaded into mating holes,i.e., plated through vias 134A, 134B in PCB 102. Such threading isfurther facilitated during assembly by the use of a specially designedassembly jig 300 (FIG. 3).

With reference now to FIG. 3, there is illustrated an exemplary assemblyjig 300 and illustrated methodology for assembly of the RFID device ofthe present subject matter. As may be seen in FIG. 3, assembly jig 300corresponds to a support block 302. Support block 302 may correspond toany suitable material able to be machined and withstand a solderingoperation without physical damage. In an exemplary device, support block302 may be made of aluminum. Support block 302 includes an upper surfaceinto which aligned channels 304, 306 running down a centerline ofsupport block 302 may be machined. Channels 304, 306 may have variouscross sections, but a preferred cross section is a semicircular crosssection of a diameter approximately that of the OD of antenna elements110, 112.

Support block 302 also has provided thereon adjustable positioningdevices 320, 322 for securing PCB 102 to support block 302. Positioningdevices 320, 322 may be made of any suitable material. As exemplarilyillustrated in FIG. 3, positioning devices 320, 322, may have providedtherein, for example, elongated slots and may be adjustably positionedrelative to channels 304, 306 and secured in place by screws 330, 332,334, 336 or by any other suitable fixing means.

Between channels 304 and 306, and between positioning device 320, 322 arecess or well 308 may be provided sized to accommodate IC device 120,if mounted, on PCB 102. For assembly, PCB 102 is turned upside down sothat IC 120, if mounted, may be positioned so as to enter recess 308 andpositioning devices 320, 322 are adjusted to secure PCB 102 in place.After securing PCB 102 to support block 302, antenna elements 310, 312are placed in channels 304, 306. Note that antenna elements 310, 312 andPCB 102 are illustrated in phantom in FIG. 3 for clarity ofillustration.

Following placement of antenna element 310 in channel 304, antennaelement 310 may be rocked back and forth as illustrated by arrows A, Bwhile being advanced in the direction of arrow C until such time as theend portion of antenna element 310 first entering notch 120A (PCB 102portions are best seen in FIG. 1D) abuts shaped portions 124A, 124B ofPCB 102. Shaped portion 124A, 124B will then guide the end of theantenna helix into plated through via 134A by virtue of the matchingpitches of shaped portions 124A, 124B, antenna element 310 and positionof plated through via 134A. After the end portion of antenna element 310enters via 134A of the upside down positioned PCB 102, the antennacontinues in an unbroken pattern through the via hole and around untilit touches the solder pad 130C where it may then be soldered in place aspreviously explained with reference to FIG. 1C. This process is repeatedfor antenna element 312 until it is soldered in place to solder pad130D.

After soldering both antenna elements in place, the assembled device maybe coated with a bonding agent and sealed within non-conductiveelastomeric material coating 150 as illustrated in FIG. 1A. It should beappreciated that assembling the RFID device in this manner produces asynergistic effect such that the bonding of the PCB and the antenna tothe elastomeric material creates a device where the whole is greaterthan the sum of the parts.

While the present subject matter has been described in detail withrespect to specific embodiments thereof, it will be appreciated thatthose skilled in the art, upon attaining an understanding of theforegoing may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, the scope of the presentdisclosure is by way of example rather than by way of limitation, andthe subject disclosure does not preclude inclusion of suchmodifications, variations and/or additions to the present subject matteras would be readily apparent to one of ordinary skill in the art.

What is claimed is:
 1. An RFID device for integration into a tire, comprising: a printed circuit board (PCB) having top and bottom surfaces delineated by opposed end portions and opposed side portions; a plurality of conductive traces on the top surface of said PCB; a notch formed in one end of said PCB; a plated through via piercing the PCB from the top surface to the bottom surface; a conductive trace element electrically coupled to said via at the top surface of said PCB, the trace element electrically coupled to the plurality of conductive traces; a conductive solder pad electrically coupled to the via at the bottom surface of said PCB and extending for a predetermined distance in the direction of the side portions of the PCB; and an antenna element having an end portion positioned within said notch, wherein a portion of said end portion passes through the via from the top surface to the bottom surface and is electrically connected to the conductive trace element coupled to said via at the bottom surface of the PCB.
 2. The device of claim 1, wherein the antenna element is in the same plane as the top surface of the PCB.
 3. The device of claim 1, further comprising an integrated circuit device mounted to the top surface of the PCB and electrically coupled to selected ones of the plurality of conductive traces.
 4. The device of claim 1, wherein the antenna element comprises a helically wound conductor.
 5. The device of claim 4, wherein the helically wound conductor is wound with a single pitch between turns.
 6. The device of claim 5, wherein the notch is provided with portions matching the pitch of the helically wound conductor.
 7. The device of claim 6, wherein the via is positioned within the PCB at a location corresponding to an extension of the pitch of the helically wound conductor from the matching notch portions.
 8. The device of claim 1, further comprising a non-conductive elastomeric material surrounding said PCB and at least a portion of said antenna element, and filling said notch.
 9. The device of claim 8, further comprising a bonding agent for securing said non-conductive elastomeric material to the antenna element and PCB.
 10. The device of claim 1, further comprising a second notch positioned at the opposing end of said PCB, a second plated through via piercing the PCB and a second antenna positioned within said second notch and in the plane defined by the top surface of the PCB. 